Telephone system and apparatus.



A. AKIN. TELEPHONE SYSTEM AND APPARATUS. APPLICATION FILED IUNE 21.1915.

1,21 1,031. Patented Jan. 2, 1917.

UNITED sT Es P EN OFFICE.

'ALL soN AKIN, or EAsT ORANGE, NEW JERSEY, ASSIGNOR, BY MESNEASSIGNMENTS, To W STE ELECTRIC COMPANY, INCORPORATED, A CORPORATION orNEW YORK.

TELEPHONE SYSTEM AND APPARATUS.

Patented Jan. 2, 1917.

A plication filed June 21, 1915. Serial No. 35,373.

To all whom it may concern: I

Be it known that I, ALLIsoN AKIN, a citizen of the United States,residing at East Orange, in the county of Essex and State of New Jersey,have invented certain new and useful Improvements in Telephone Systemsand Apparatus, of which the following is a full, clear, concise, andexact description.

This invention relates to telephone switching systems and apparatustherefor, and more particularly to a combined electromagnetic signalcontrolling relay and impedance coil for a bridged impedance type oflink circuit.

The object of this invention in general is to produce a simple relay ofeconomical form which may be'connected in bridge of the strands of acord circuit in series with the battery which supplies current to thetransmitter at the way station, which will operate at high efliciencupon direct cur rents and will afford su cient impedance to alternatingcurrents of high frequencies to In accordance with the general featuresof this invention, there is provided a relay having two windingsconnected with the strands of a cord, circuit and comprising a structurein which there are provided a plurality of magnetic paths of differentlengths which prevent complete saturation of the core with a superposeddirect current flowing through the windings. A form of relay embodyingthe characteristics required to make this invention successful is one inwhich the core, which is preferably of a larger cross-sectional areathan the cross-sectional area of the armature, is formed of laminae,which constitute with the armature a plurality of separate magneticpaths including air-gaps of different lengths. The armature of the relayis mounted to move in a direction transverse to the longitudinal axis ofthe core.

In the drawings illustrating this invention, Figure 1 is a diagram of acord circuit and apparatus embodying the features of this invention;Fig. 2 is a view in side elevation of a relay made in accordance withthis invention, and Fig. 3 is an end view of the relay.

As shown in Fig. l, 5 and 6 designate subscribers telephone linesterminating at one end in the usual subscribers equipments 7 and 8, andat the other end in line jacks 9 and 10, and having connected with themthe usual line and cutoff relays 11, 11 and 12, 12. A cord or linkcircuit'comprising strands 1G and 17 divided by means of condensers 18and 19 and having plugs 20 and 21 connected with its strands, is adaptedto connect the two subscribers lines by the insertion of the plugs 20and 21 into the line jacks 9 and 10. A relay 2 1 having two windings 25and 26 has these windings connected with the strands 17 and 16respectively and in series with a grounded source of energy 27. Thisrelay 24.- controls a supervis'ory signal 28 and is actuated over acircuit including the line Wires when the subscribers receiver isremoved from the switchhook.

The relay 21 is substantially the same mechanically as the relay shownand described in the Craft Patent 1,121,897 of December 1911. The relayof this in vention difi'ers, however, from the relay shown in the Craftpatent in that the core prevent the shunting of the voice currents.30thereof is made up of sheets 31, 31 of magnetic material which sheetsare clamped together to form a core which is considerably larger incross-sectional area than the armature 32. The armature 32, which is Ushaped, is mounted upon a rearward extension of the core 30 and isadapted to move in a direction transverse to the longitudinal axis ofthe core. By reason of this construction there are provided a pluralityof separate magnetic circuits including the relay armature 32 and theseparate laminae, each magnetic circuit having an air-gap different inlength from the other depending upon the distance from the armature ofthe separate laminae comprising the core. Due to the largecross-sectional area of the core 30 compared with that of the armature32, and to the fact that there are a plurality of magnetic circuits eachincluding an airgap, the armature will pull up readily in response toenergizing current in the wind ings, but the core 30 will not becomeentirely saturated. For example, when the armature is in attractedposition, the lamina to which the armature is adjacent forms with thearmature a magnetic path of low reluctance compared to the pathincluding the armature, the outermost lamina and the interveningsections of the intermediate laminae and associated non-magnetic gaps.Therefore, with a given number of ampereturns of magnetizing forceproduced by the relay Winding, the portion of the core adjacent to thearmature will have a much higher flux density than the most remoteportion or any intermediate portion. It follows then that enoughmagnetizing force to just saturate the armature and the adjacent portionof the core Will not saturate the portions farther removed, Which is thecase under service conditions. Another action also takes place in relaysof this construction which has previously not advantageously been madeuse of in relay design, and that is the Well-known demagnetizing effectof ends in a magnetic circuit. Any magnetic path with nonmagnetic gapstherein tends to oppose the flux How and hence the degree ofmagnetization Which a given magnetomotive force can produce. In thisinvention this phenomenon is advantageously made use of to limit thedegree of magnetization in the portions of the core removed from thearmature; since, as has been hereinbefore pointed out, the magneticpaths of which such portions form a part have non-mag netic gapstherein. Due to the fact then that a part of the core is unsaturated andtherefore of high permeability to small high frequency currents therelay gives satisfactory retardation effects at telephonic frequencies,and the bridge containing this relay will be opaque to alternatingcurrents of talking frequencies. A relay of this type can be casilyproduced at a slight cost, and it has been determined that With such arelay in the cord circuit the transmission efiiciency compares favorablyWith that of the standard repeating coil cord circuits.

lVhat is claimed is:

1. A relay comprising an armature of magnetic material, a core, composedof superposed layers of magnetic and non-magnetic material at varyingdistances from said armature to provide magnetic paths of differentlengths for increasing the difierence in the magnetic density of thecore at points near to and remote from the armature and an energizingWinding for said core and armature.

2. In an electromagnetic device, a core composed of a plurality oflaminae separated by non-magnetic gaps an armature of mag netic materialin operative relation thereto and adapted to move toward the core in adirection transverse to the plane of said laminae, whereby the coreforms a plurality of magnetic paths of difi'erent lengths havingnon-magnetic gaps therein.

In Witness whereof, I hereunto subscribe my name this 17 day of June A.D., 1915.

ALLISON AKIN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

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